WO2015055711A1 - Method and device for producing particles in an atmospheric pressure plasma - Google Patents

Method and device for producing particles in an atmospheric pressure plasma

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Publication number
WO2015055711A1
WO2015055711A1 PCT/EP2014/072106 EP2014072106W WO2015055711A1 WO 2015055711 A1 WO2015055711 A1 WO 2015055711A1 EP 2014072106 W EP2014072106 W EP 2014072106W WO 2015055711 A1 WO2015055711 A1 WO 2015055711A1
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WO
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Application
Patent type
Prior art keywords
electrode
sacrificial
discharge
region
cooling
Prior art date
Application number
PCT/EP2014/072106
Other languages
German (de)
French (fr)
Inventor
Jörg IHDE
Ralph Wilken
Jost Degenhardt
Sergey Stepanov
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/228Gas flow assisted PVD deposition
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/24Vacuum evaporation
    • C23C14/32Vacuum evaporation by explosion; by evaporation and subsequent ionisation of the vapours, e.g. ion-plating
    • C23C14/325Electric arc evaporation
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00Generating plasma; Handling plasma
    • H05H1/24Generating plasma
    • H05H1/26Plasma torches
    • H05H1/32Plasma torches using an arc
    • H05H1/42Plasma torches using an arc with provisions for introducing materials into the plasma, e.g. powder, liquid
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00Generating plasma; Handling plasma
    • H05H1/24Generating plasma
    • H05H1/48Generating plasma using an arc
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H2240/00Test
    • H05H2240/10Test at atmospheric pressure

Abstract

The invention relates to a method for producing particles (30) using an atmospheric pressure plasma, in which the plasma is generated by a discharge (15, 15') between electrodes (16, 16', 16"; 5, 32) in a process gas (18), and at least one of the electrodes is a sacrificial electrode (16, 16', 16") from which material is removed by the discharge, wherein the removed material is particles and/or particles arise from the removed material. A portion of the sacrificial electrode is actively cooled so that the mean temperature of the sacrificial electrode, in a region of the sacrificial electrode outside of the discharge region (17, 17', 17") of the sacrificial electrode, is lower than within the discharge region of the sacrificial electrode. The invention also relates to a device for producing particles (30) using an atmospheric pressure plasma, which comprises: a housing (5) having a channel (7, 7', 7"), at least two electrodes (16, 16', 16"; 5, 32) which are arranged at least partially in the channel, and a voltage source (22) which is designed to apply a voltage between the at least two electrodes. The at least two electrodes are designed to generate the plasma by a discharge (15, 15') between the electrodes in a process gas (18) in the channel, and at least one of the electrodes is a sacrificial electrode (16, 16', 16") from which material is removed by the discharge, wherein the removed material is particles and/or particles arise from the removed material. The device further comprises a cooling device (2) which is designed to actively cool a portion of the sacrificial electrode so that the mean temperature of the sacrificial electrode, in a region of the sacrificial electrode outside of the discharge region (17, 17', 17") of the sacrificial electrode, is lower than within the discharge region of the sacrificial electrode.

Description

METHOD AND APPARATUS FOR THE PRODUCTION OF PARTICLES IN A

ATMOSPHERIC PRESSURE PLASMA

FIELD OF THE INVENTION

The present invention relates in a first aspect a method for the preparation of particles using an atmospheric-pressure plasma. With the method can be formed efficiently particles, particularly micro- and nanoparticles. According to a further aspect, the invention relates to an apparatus for producing particles, particularly micro- and nanoparticles, using an atmospheric pressure plasma.

STATE OF THE ART

Micro- and nanoparticles are for several years of service in various fields of technology to modify the properties of products. For example, optical, electrical (for example, conductivity), thermal (eg thermal conductivity), electro-magnetic and mechanical properties (such as stability or abrasion resistance) can be improved by the incorporation of such particles.

To satisfy the demand for such particles, various methods have been proposed.

Here, the low-pressure process are first of all to call.

The DE-A-198 24 364, for example, relates to a method for applying wear-resistant layers with optical properties to surfaces. The method comprises at least two different

Abscheidesch rode. One step is a plasma enhanced CVD process for Abscheid ung antiwear a matrix and the other step is a material deposition by means of a PVD technique for storing optically functional material in the matrix. The used PVD technique may be, for example, a sputtering method.

WO 2005/061754 relates to a method for manufacturing a functional layer, wherein a deposition material under the influence of the plasma is deposited on a substrate and simultaneously at least one second material by a second deposition process is applied to the substrate. As a second

Abscheid ungs know is, among other PVD, such as sputtering, called.

WO 2005/048708 deals with a antimikrobieilen and non-cytotoxic layer material, comprising a biocide layer and a layer covering this transport control layer. In embodiment 6 of this document, the biocide layer is applied by a low-pressure DC magnetron sputtering process and

Transport control layer applied by a plasma polymerization process in a second working step. Atle iederdruckverfahren provide high equipment requirements, as vacuum chambers are required, usually only allow low deposition rates (in the range of a few nm / s) and make masks required to coat locally. Furthermore, there is due to the limited capacity of

Vacuum chambers limits with regard to the size of substrates or components that can be coated.

To avoid these disadvantages of the low-pressure method, atmospheric pressure plasma processes have been suggested.

For example, in DE-A-199 58 473 uses a Plasmastrahiquelle, which is said that they can be operated in fine vacuum to near-atmospheric pressure range. is specifically described the simultaneous deposition of a matrix layer and embedded therein particles as a function of coating. For this purpose a microscale or nanoscale metal powders such as TiN powder via the gas supply, is introduced together with a carrier gas into the plasma.

The DE-A-198 07 086 relates to a process for coating substrate surfaces in a plasma-activated process at atmospheric pressure. Here, a gas phase, which may contain a powdery solid is introduced into the plasma jet.

Also, in WO 01/32949 a precursor material is fed into the plasma jet, so as to coat surfaces. The precursor material can contain solid, for example pulverulent constituents. Thus, particles can be embedded in the deposited layers.

All the above-described atmospheric pressure plasma method for producing layers with dlspergierten therein particles is common that the particles, for example in the form of powders, are fed from the outside into the plasma jet. This procedure entails considerable problems when microparticles especially when nanoparticles are to be installed in layers and. The reason is that microparticles and nanoparticles especially when they are in the form of powders tend strongly to agglomerate.

The DE-B-23 865 102 relates to a process for the plasma coating of workpieces, in which a beam of an atmospheric plasma is generated by means of a plasma by high frequency electrical discharge, by which the swept workpiece to be coated surface. The method is characterized in that at least one component of the coating material is contained as a solid in an electrode of the plasma nozzle and is sputtered by the RF discharge from the electrode, appears from DE-B-102 23 865, the sputtered material is predominantly in the form of very more reactive ions or radicals before. These species form homogeneous coatings according to the teaching of this patent, for example, metals or metal compounds. The generation of particles, let alone micro or

Nanoparticles is not disclosed in DE-B-102 23 865th

The US 5,808,270 relates to an apparatus and a method for thermal plasma spraying üchtbogen- metal wire, produced by the an extended arc and a supersonic plasma jet. A serving as an anode metal wire is introduced continuously into the plasma jet, where the extended Plasmaiichtbogen skips to the wire tip, melting the wire, and the Überschali plasma beam atomizes the molten metal particles and carries them off in order to form a coating. Also, US 5,808,270 does not teach a generation of particles, much of micro- or nanoparticles.

The DE-B-10 2009 031 857 discloses a plasma torch for cutting a material by means of a high-energy plasma jet. Because the high energy density of the plasma beam leads to a thermal load of a nozzle of the plasma torch, it is cooled in order to extend their service life. A Hersteilung of particles does not take place in the plasma torch.

The DE-A-10 2009 048 397 relates to a process for the preparation of surface-modified particles in an atmospheric pressure plasma using a sputter, are sputtered from the discharge by a particle. In order to prevent an excessive increase in the temperature at the sputter electrode, is taught by DE-A-10 2009 048 397 to limit a discharge caused by the power input to the sputtering electrode, by a discharge generating voltage generator is operated in a pulsed or

is rotated sputter or oscillates.

This limitation of the Leistungsetntrags to the sputter electrode leads to a decrease in the sputtering yield, ie the Hersteilrate of the particles, so that, for example, long coating times are required to deposit the particles on a surface of a substrate. Therefore, the realizable

Coating speeds, so that a process-related heat flow can lead to substrate damage or the small number of cycles large or the substrates to be treated are limited due to the allowable temperature limit. Moreover, the obtainable concentration of separated particles on a surface to be coated is limited since the particles can be at high concentrations, especially at higher temperatures, combine to form larger clusters or agglomerate.

The invention has for its object to provide a method and an apparatus for the preparation of particles using an atmospheric-pressure plasma that allow efficient production of particles, in particular of microparticles and nanoparticles, high production rate and controlled particle size distribution. SUMMARY OF THE INVENTION

This object is according to the invention by the method according to independent claim 1 and the

Apparatus according to independent claim 17 dissolved. Advantageous embodiments of the invention follow from the dependent claims.

According to the first aspect, the present invention provides a method for the preparation of particles using an atmospheric pressure plasma prepared in which the plasma is generated by a discharge between electrodes in a process gas, at least one of the electrodes, a sacrificial electrode, or

is target electrode, is removed, or by the discharge material peeled off it (i) in the removed material are particles and / or (ii) from the removed material particles are formed, and a portion of the sacrificial electrode is actively cooled so that the average temperature of the sacrificial electrode in an area of ​​the sacrificial electrode outside the discharge area of ​​the sacrificial electrode is lower than within the

Discharge area of ​​the sacrificial electrode.

The term "area of ​​the sacrificial electrode outside the discharge area of ​​the sacrificial electrode" refers to the entire area of ​​the sacrificial electrode, which lies outside the discharge area of ​​the sacrificial electrode.

According to the inventive method, at least a portion of the sacrificial electrode is actively cooled.

The terms "sacrificial electrode" and "target electrode" are used interchangeably herein.

Particles may be created or formed by agglomeration processes of the removed material, particularly in a relaxation region of the atmospheric pressure plasma. Specifically, it can occur in the period between the removal of the material of the sacrificial electrode and any deposition of the particles on the surface of a substrate for formation or formation of particles. The results showed that the occurrence or formation of particles takes place primarily in a relaxation region of the atmospheric pressure plasma. The inventors have found that in the process according to the invention, the yield of particles, especially nanoparticles, by controlling the dwell time of the material in the relaxation region of the atmospheric pressure plasma can be further increased. The residence time in the relaxation region of

Atmospheric pressure plasma, by increasing the path length in the region of the relaxant

Atmospheric pressure plasma are increased.

Control of the residence time is advantageously carried out in the light of the finding that the yield of nano Parti No can be further increased by increasing the residence time of the material in the relaxation region of atmospheric pressure plasma at first, there being an upper limit of the residence time, of the at it to increased formation larger particles, in particular microparticles comes.

An "active" plasma region, a plasma region is generally understood, which is located within the volume bounded by the electrodes between which a voltage is applied, through which the plasma is generated. In the active plasma region free electrons and ions are separated before ,

On the other hand there is the relaxation region of the plasma outside the excitation zone which is bounded by said electrodes. The relaxation region of the plasma is sometimes referred to as "after gtow" - designated area in the relaxation region of the plasma no free electrons and ions are more, rather excited atoms or molecules..

The relaxation region of the atmospheric pressure plasma in the case of a plasma nozzle, the area on the downstream side of the excitation zone (ie starting at the electrode closer to the outlet of the plasma), which is delimited by the end of the visible plasma flame. Typically, the plasma flame extends approximately 10 mm beyond the Austass the plasma addition.

In a standard Atmosphärendruckplasmadüse is the distance between the electrode which is closer to the outlet of the plasma nozzle and the outlet is typically in the range of 2-5 mm. As the inventors have found the yield of nanoparticles, compared with the above-mentioned standard Atmosphärendruckplasmadüse significantly greater when a Atmosphärendruckplasmadüse with a distance between the electrode which is closer to the outlet of the plasma nozzle and the outlet of the nozzle of about 50 mm has been used. In both cases, the length of the plasma flame, extending over the outlet of the plasma nozzle addition was comparable in size (about 10 mm).

As an electrode in the inventive sense of each element, for example, each part of the apparatus used for the inventive method, especially a plasma understood that is at least at times, to start or end of the Entladungsfilaments.

For the purposes of the present application, the electrode is removed or replaced from that in the inventive process by generating the plasma discharge material, as a "sacrificial electrode" or

designated "target electrode". In the inventive method, a plurality of electrodes, in particular electrodes of the same or different electrode materials may be sacrificial electrodes, but may also be just one of the electrodes sacrificial electrode.

.. The term "atmospheric pressure plasma", which is also referred to as AD-plasma or atmospheric pressure plasma is meant a plasma, in which the pressure is approximately equal to the atmospheric pressure C. tendero et al provide in "Atmospheric pressure plasmas: A review", Spectrochimica Acta Part B: Atomic Spectroscopy, 2006, pp 2-30 an overview of atmospheric pressure plasmas.

The term "particles" refers to particles of a given material, in particular macroscopic particles in delineation of individual atoms or molecules or clusters thereof.

The term "average temperature of the sacrificial electrode" refers to the temporal and spatial mean value of the temperature, ie, the average of the temperature for a certain period, namely the period during which the discharge takes place, and over a certain Fiächenbereich the sacrificial electrode, such as the Entiadungsbereich the sacrificial electrode or the area of ​​the sacrificial electrode outside the discharge region.

The discharge region of the sacrificial electrode is of the region of the sacrificial electrode, in which the discharge takes place predominantly. The term "predominantly" is defined herein that the discharge region of the sacrificial electrode is of the region of the sacrificial electrode, in which the discharge takes place over a period of 50% or more of the entire

Discharge period is, that is the period in which the discharge takes place on the sacrificial electrode.

By actively cooling the portion of the sacrificial electrode which caused by the discharge increase TE1 of the average temperature of the sacrificial electrode falls within the portion of the sacrificial electrode after turning off the discharge within a period of no more than 4 minutes, preferably not more than 3 min, more preferably no more than 2 minutes, more preferably not more than 1 min, and most preferably not more than 40 s, χ to a value of 1 / e from TE1, where e is Euler's number. Active cooling is provided by a cooling device.

The sacrificial electrode consists of an electrically and thermally conductive material, such as metal.

According to the inventive method, the portion of the sacrificial electrode is actively cooled so that the average temperature of the sacrificial electrode in the region of the sacrificial electrode outside the discharge region of the

sacrificial electrode is lower than within the discharge region of the sacrificial electrode. Consequently, there is a

Temperature difference or a temperature gradient between the discharge region and the region of the

Sacrificial electrode outside the discharge area, can be so that heating of the discharge region through the discharge by heat transfer from the discharge region to the area of ​​the sacrificial electrode compensated or balanced outside the discharge region.

Thus, excessive heating of the sacrificial electrode or sacrificial electrodes may also be at a high power input by the discharge in relation to the surface of the sacrificial electrode or sacrificial electrodes are avoided, so that a so-called spalling of material, is reliably prevented. In this way, a

undesired large surface melting of Opferelektrodenmateriai and thus a transfer of spratzigem material on the substrate surface can be avoided. Therefore, it can be achieved, in particular by the thus possible high power input to the Opfereiektrode or sacrificial electrodes, a high manufacturing or production rate of the particles, while the particle size is kept small and the size distribution of the particles can be accurately controlled or controlled. Consequently, an efficient production of particles is made possible with a defined size.

Furthermore, also temperature sensitive substrate materials are coated on a surface of a substrate due to the higher production rate and thus also higher deposition efficiency of the particles during the deposition of the particles as the process times and thus the heat input per time and surface is significantly reduced.

The inventive method can also be combined with a chemical vapor deposition process (CVD), in particular in one step, in particular to a continuous layer having dispersed therein particles form. In this case, the inventive method enables a balanced and uniform concentration of particles in the layer. Moreover, the concentration of particles in the layer compared to processes without active cooling can be significantly increased.

The portion of the sacrificial electrode may be actively cooled so that the average temperature of the sacrificial electrode in an area of ​​the sacrificial electrode in which no material is removed, is lower than in an area of ​​the sacrificial electrode is removed in the material.

The portion of the sacrificial electrode may be actively cooled so that the average temperature of a part of the Opfereiektrode, which is located in the region of the discharge, is higher than the average temperature of a part of the Opfereiektrode, which is located outside of the discharge.

The discharge area of ​​the sacrificial electrode can be an excellent geometric region of the sacrificial electrode. Under a geometric excellent area, a range is understood in the sense of the present application, in the concentrates because of the prevailing high field strength discharge. Typical examples of such geometric areas excellent in electrodes are peaks, edges and corners.

In the inventive method, the entire sacrificial electrode, so the discharge area of ​​the Opfereiektrode and the range of O can ferelektrode outside of the discharge region, are actively cooled.

The cooling of the portion of the sacrificial electrode or sacrificial electrodes can be made via thermal conduction. Since heat conduction allows a quick and effective heat dissipation from the sacrificial electrode, the sacrificial electrode can be cooled in a particularly efficient manner. The cooling of the portion of the sacrificial electrode or sacrificial electrodes can be effected by a cooling medium or coolant. The cooling medium or cooling medium may be a solid, liquid or gaseous cooling medium or coolant. As cooling medium, in particular water, water-glycol, ethanol dry ice, liquid nitrogen, CO2 ice etc. may be used. The cooling by a cooling medium enables a particularly simple and effective cooling of the sacrificial electrode. a liquid cooling medium or refrigerant is particularly preferably used.

According to one embodiment of the present invention, the coolant contacts only the portion of sacrificial electrode outside the discharge region of the sacrificial electrode, or only with a part of the area of ​​the sacrificial electrode outside the discharge area of ​​the sacrificial electrode into contact. In this way, the region of the sacrificial electrode outside the discharge region can be efficiently cooled, whereby a deterioration of the discharge in the discharge region is particularly reliably avoided by the cooling operation. Moreover, by the cooling caused by the high temperature difference between the cooling medium cooled by the area of ​​the sacrificial electrode outside the discharge area and the discharge area a fast

ensures heat removal from the discharge area.

According to one embodiment of the present invention, the sacrificial electrode occurs at an entry point of the sacrificial electrode to a cooling range within which the portion of the sacrificial electrode is actively cooled, where the entry point at a side opposite to the discharge area of ​​the sacrificial electrode side of the cooling range, and is the difference between the average temperature of the sacrificial electrode within the Entiadungsbereichs the sacrificial electrode and the average temperature of the sacrificial electrode at the entry point in the range of Ts 393 K to Ts - 77 K, preferably T s - 373 K to Ts - 77 K, more preferably from T s - 323 K to Ts - 77 K, and most preferably of T s - 293 K to T s - 77 K, where T s is the melting temperature of the material of the sacrificial electrode in Kelvin (K).

The cooling region may be the cooling device or a part of the cooling device. The sacrificial electrode may come into the cooling region with a solid, liquid or gaseous cooling medium in contact, particularly in direct or indirect contact or direct or thermal.

a spalling of material of the sacrificial electrode is avoided in this way a particularly efficient heat dissipation from the discharge area of ​​the sacrificial electrode can be ensured and melting of the sacrificial electrode in the discharge region are prevented particularly reliably, so that even with a high power input to the sacrificial electrode.

By actively cooling the portion of the sacrificial electrode which caused by the discharge increase can TE2 of the average temperature of the sacrificial electrode min at the entry point after turning off the discharge within a period of not more than 4, preferably not more than 3 min, more preferably not more than 2 min, more preferably not more than 1 min, and most preferably not more than 40 s, to drop to a value of 1 / e χ TE2. The Opfereiektrode may be at least partially disposed in a channel of a housing. The housing may be the housing of a plasma nozzle. The channel can be flowed through by the process gas. A portion of the sacrificial electrode may be disposed in the housing outside the passage and / or outside the housing.

The cooling medium can, in particular, come with a part or region of the sacrificial electrode is in contact, particularly in direct and immediate, so physical, or thermal or indirect contact, which is arranged in the housing outside the passage and / or outside the housing. In particular, the cooling medium can only with this area in contact, particularly in direct or indirect contact or direct or thermal come.

The thermal or indirect contact is performed by a secondary medium, such as a wall or wärmeieitfähige wall disposed between the cooling medium and the part or region of the sacrificial electrode. For example, the sacrificial electrode may at least partially be performed by a wärmeieitfähige tube or the like. Active cooling of a portion of the sacrificial electrode may be effected by direct contact of the tube with the cooling medium.

According to one embodiment of the present invention, the sacrificial electrode occurs at an entry point of the sacrificial electrode to a cooling range within which the portion of the sacrificial electrode is actively cooled, where the entry point at a side opposite to the discharge area of ​​the Opfereiektrode side of the cooling range, and exceeds the average temperature of the sacrificial electrode in the entry region is not 393 K, preferably not 373 K, preferably not 323 K, and most preferably not 293 K. in this way it is ensured a particularly efficient heat removal from the discharge region of the sacrificial electrode. For these middle

Temperatures of the sacrificial electrode to the point of entry may, in particular, the difference between the mean temperature of the sacrificial electrode within the discharge region of the sacrificial electrode and the average temperature of the sacrificial electrode at the entry point in the range of Ts - 393 K to Ts - 77 K, preferably from Ts - 373 K to Ts - 77 K, more preferably from Ts - 323 K to Ts - 77 K, and most preferably from Ts - 293 K to Ts - 77 K, are.

In the inventive method, the average temperature of the sacrificial electrode may be within the

be the discharge portion of the sacrificial electrode selected so that it does not exceed the melting temperature of the material of the sacrificial electrode. Consequently, a melting of the discharge area of ​​the sacrificial electrode and thus a spalling of sacrificial electrode material is particularly reliably avoided.

The sacrificial electrode may have an elongated shape. For the purposes of the present application, the term "oblong shape" means a shape whose dimension is larger in one dimension, in particular considerably greater than in the other two dimensions. In particular, the sacrificial electrode may be a wire, a rod or a Hohlprofii, including an elongated hollow profile be.

The discharge region may be located at one end of the elongated sacrificial electrode, in particular a wire. The end of the elongated sacrificial electrode may be in the form of a tip, in particular a wire tip, are present. According to one embodiment of the present invention, the elongated sacrificial electrode, in particular the wire rod or the elongate hollow profile, an average diameter of 0.1 to 20 mm, preferably from 0.1 to 10 mm, preferably from 0.1 to 5 mm and more preferably from 0.5 to 1, 5 mm.

The sacrificial electrode may be introduced perpendicular to the flow direction of the process gas in the plasma in the plasma parallel to a flow direction of the process gas in the plasma or in a direction in one direction. In the case of an elongated sacrificial electrode, the longitudinal axis of the sacrificial electrode may be parallel to the flow direction of the process gas in the plasma or perpendicular to the flow direction of the

Process gas lie in the plasma.

A concentration of discharge on a limited region of the sacrificial electrode or sacrificial electrodes can be promoted by the gas flow of the process gas. This proves to be, for example, a directional wirbeiförmige flow of the process gas that can be generated by a twisting device, to be advantageous.

As a materialist! the sacrificial electrode or sacrificial electrodes, metals such as copper, aluminum, indium, zinc, titanium and magnesium, in particular precious metals, such as gold, silver, platinum and palladium, but also metal alloys, metal oxides (such as BaO, zinc oxide, tin oxide) and carbon in question. In addition, the Opferetektrode can be made of aluminum bronze.

Removing material of the sacrificial electrode may be favored by the choice of electrode material. Silver, for example, a material of which can be very easily remove material. In particular, an effective material removal for conventional electrode geometries can be achieved for silver electrodes.

In the inventive method, the position of the discharge region of the sacrificial electrode may, for example, by a nrichtung Erfassungsei, in particular an optical and / or electronic

Detecting means are recorded, are recorded in particular visually and / or electronically. For example, the optical detection of the position of the discharge region of the sacrificial electrode through an endoscope can be made.

The term "position of the discharge area of ​​the sacrificial electrode" herein refers to the position of

Discharge region of the sacrificial electrode relative to a housing of an apparatus for producing particles, such as a plasma, in which the sacrificial electrode is provided. Thus, a change of this position or a deviation of this position from a predetermined position can be reliably and accurately determined.

According to one embodiment of the present invention, the sacrificial electrode is guided or moved so that the position of the discharge region of the sacrificial electrode, for example, remains relatively unchanged or equal to the housing, during the process, thus during the implementation of the method, substantially.

In this way, can be particularly reliably ensured that both the production rate of the particles and the size distribution of the particles remains substantially unchanged.

Moreover, it can be ensured that neither too much nor too little sacrifice electrode material in the process gas, for example in the channel of the housing is present. If too little sacrifice electrode material in the

Discharge channel is present, the formation of a sufficient temperature difference between the discharge region and the region of the sacrificial electrode outside the discharge region is made more difficult, so that the cooling efficiency can be impaired. On the other hand, the presence of too much

ungskanal adversely affect Opfereiektrodenmaterial in the UNLOAD particle generation efficiency.

For example, the sacrificial electrode may be a trackable sacrificial electrode, in particular a trackable wire sacrificial electrode to be. For the purposes of the present application "repositionable" means in connection with an electrode, that the position of the discharge region of the sacrificial electrode by subsequent pushing or

can be controlled retraction of the sacrificial electrode or set.

The sacrificial electrode may be performed based on the detected position of the discharge region of the sacrificial electrode so or moved so that the position of the discharge region of the sacrificial electrode, in spite of the process-related material removal, remains the same and unchanged during the process substantially.

This approach allows a particularly accurate and reliable adjustment of the position of the discharge region. In particular, the process can be automated or the corresponding guide movement of the sacrificial electrode based on the detected position, for example by means of a feedback loop or a feedback loop.

The discharge may be a pulsed or pulsating discharge. The pulsed or pulsating discharge can in particular by a pulsed or pulsed operation of a voltage source, such as a generator, are generated, which is adapted to a voltage (for example, DC), in particular a high voltage to be applied between the electrodes, and with which the discharge , which is preferably a

Arc is, is effected. In this way, a pulsed or pulsed voltage can be generated. Preferably, an asymmetrical alternating current voltage is generated. The pulse frequency of the voltage source, for example, the generator is not particularly limited and may be 5 to 70 kHz, with the range of 15 to 40 kHz is preferred. For carrying out the process according to the invention have pulse rates 16 to 25, in particular 17 to 23 kHz, proved to be particularly advantageous.

Suitable process gases that can be used for example in plasma jets are known to the expert. For example, nitrogen, oxygen, hydrogen, inert gases (particularly argon), ammonia (NH3), hydrogen sulfide (H2S), and mixtures thereof, in particular compressed air, nitrogen-hydrogen mixtures and rare gas-hydrogen mixtures are used.

The flow rate of the process gas through the Atmosphärend ruckpiasma is not particularly limited and may for example be in the range from 300 to 10,000 l / h. Since it has been shown that lower flow rates of the process gas tends to increase the Partikeiausbeute, the flow rate is according to the invention preferably in the range of 500 to 4000 l / h.

The particles are preferably transported in the present process from the process gas, in particular transported away from the discharge region of the Opfereiektrode.

Preferably, the particles micro- and / or nanoparticles. For the purposes of the present application, particles are understood as micro- and Nanopartiketn whose diameter is in the range of micro- or nanometers. The particles may μιτι a particle size or a particle diameter in the range of 2 nm to 20, preferably from 5 nm to 10 pm, more preferably μιτι from 10 nm to 5, more preferably μηη from 10 nm to 1, and most preferably from 10 nm to 200 nm. The particle size or the particle diameter of the particles can μιτι also in a range of 2 nm to 10, 2 nm to 5 μη, μηι 5 nm to 5, 2 nm μηι to 1, μιη 5 nm to 1, 2 nm to 200 nm, 5 nm to 200 nm, 20 nm to 200 nm or 50 nm to 200 nm.

Such micro- and / or nanoparticles may be prepared by the inventive process with high production rate and controlled Parti kelg rößenverteitu ng are generated, as has been explained above in detail.

According to a particularly preferred embodiment of the present invention, the particles are nanoparticles, ie by particles whose diameter is in the nanometer range, in particular in the range of 2 to 100 nm.

Further, the average (volume-average) particle diameter of the particles is preferably in the range of nano- or micrometers, more preferably μιη in the range of 2 nm to 20, most preferably in the range of 2 to 100 nm. The determination of the particle size of very small particles, such as nanoparticles, for example, with

Laser scattering method or transmission electron (TE) possible. For larger particles, the sieve analysis and centrifugation are available.

According to a further aspect, the present invention relates to a process for the preparation of particles using an atmospheric pressure plasma, particularly in an atmospheric-pressure plasma, wherein the plasma is generated by a discharge between electrodes in a process gas, at least one of the electrodes is a sacrificial electrode from which by the discharge material is removed, it is (i) wherein the removed material consists of particles and / or (ii) from the removed material particles are formed, and the sacrificial electrode is guided or moved so that the position of the discharge region of the sacrificial electrode during the process , therefore, remains substantially the same during the execution of the process.

The position of the discharge region of the sacrificial electrode may, in particular visually and / or electronically, for example be detected by an endoscope.

The sacrificial electrode may be performed based on the detected position of the discharge region of the sacrificial electrode so or moved so that the position of the discharge region of the sacrificial electrode, in spite of the process-related material removal, remains the same during the process substantially.

According to a further aspect, the present invention relates to a device for the preparation of particles using an atmospheric pressure plasma, particularly in an atmospheric pressure plasma. The apparatus comprises a housing having a channel, at least two electrodes which are at least partially disposed in the channel, and a voltage source which is adapted to a voltage (for example, DC), in particular a high voltage to be applied between the at least two electrodes, at least two electrodes are adapted to generate the plasma by a discharge between the electrodes in a process gas in the channel, and at least one of the electrodes is a sacrificial electrode is removed from the through the discharge material, and at the removed material consists of particles and / or arising from the removed material particles.

In addition, the inventive device includes a cooling device which is configured to actively cool a portion of the sacrificial electrode so that the average temperature of the sacrificial electrode in an area of ​​the sacrificial electrode outside the discharge area of ​​the sacrificial electrode is lower than within the

Discharge area of ​​the sacrificial electrode. The inventive device provides the advantageous effects that have already been described above in detail for the inventive method. In particular, the device allows production of particles with high production rate at a controlled particle size distribution and small particle sizes.

The cooling means may be adapted to cool the portion of the sacrificial electrode so that the average temperature of the sacrificial electrode is lower in a region of the sacrificial electrode, in the ablated no material or replaced removed in the material than in a region of the sacrificial electrode, or will be replaced.

The cooling means may be adapted to cool the portion of the sacrificial electrode so that the average temperature of a portion of the sacrificial electrode, which is located in the region of the discharge, is higher than the average temperature of a portion of the sacrificial electrode, which is located outside of the discharge.

The inventive device may comprise a PSasmadüse or be formed as plasma.

Using the apparatus according to the invention, in particular when this is designed as a plasma nozzle, the particles produced can be applied specifically, for example, from an outlet of the channel or the housing. Consequently, a local coating of the particles prepared can be performed on the surface of a substrate.

For example, the device, in particular a plasma nozzle may be moved relative to the substrate during spraying or deposition of the particles, for example through the outlet of the channel or the housing, on the surface of the substrate can. In particular, the device can be moved relative to the substrate in one direction or multiple directions, that is parallel to the surface of the substrate is substantially or lie. In this way, a precisely controlled local application of the particles produced is allowed on the surface of the substrate.

The relative velocity between the inventive device, in particular the plasma nozzle and the substrate to be coated may be in the range of mm / s to m / s and for example be up to 200 m / min. By said relative speed the Partikelabscheidemenge per area can be adjusted.

In addition, the amount deposited per unit area can, set on the repetition of the deposition process, ie the number of cycles. The increase in the relative speed at the same time increasing the number of cycles may be particularly advantageous when temperature-sensitive materials such as polymers. The distance between device, in particular plasma, and the substrate, which affects also the Partikelabscheidemenge per area may, 1 mm to several cm, for example, a maximum of 10 cm be.

The apparatus may further comprise a gas supply means which is adapted to supply a process gas into the channel of the housing. The cooling device can be adapted to cool the portion of the sacrificial electrode via thermal conduction.

The cooling means may be adapted to cool the portion of the sacrificial electrode by a cooling medium or coolant, for example, a solid, liquid or gaseous cooling medium or coolant.

The cooling device can be arranged so that the cooling medium or coolant contacts only the portion of sacrificial electrode outside the discharge region of the sacrificial electrode into contact.

The cooling device can be arranged so that the sacrificial electrode does not come into direct contact with the cooling medium, but by thermal contact with a fixed wall, preferably by heat conduction, is cooled.

According to one embodiment of the present invention, the sacrificial electrode occurs at an entry point of the sacrificial electrode to a cooling range within which the portion of the sacrificial electrode is actively cooled, wherein the entry Steep opposite to a the discharge region of the sacrificial electrode side of the cooling range ,, and the cooling device so arranged such that in operation of the device, in particular during stationary operation of the apparatus, the difference between the mean temperature of the sacrificial electrode within the discharge region of the sacrificial electrode and the average temperature of the sacrificial electrode at the entry point in the range of Ts - 77 K - 393 K to Ts , preferably from T s - 373 K to T s - 77 K, more preferably from T s - 323 K to T s - 77 K, and most preferably of T s - 293 K to Ts - 77 K, is where T s is the melting temperature is the material of the sacrificial electrode in Kelvin (K).

The cooling region may be the cooling device or a part of the cooling device. The sacrificial electrode may come into the Kühiungsbereich with a solid, liquid or gaseous cooling medium in contact, particularly in direct or indirect contact or direct or thermal.

According to one embodiment of the present invention, the sacrificial electrode occurs at an entry point of the sacrificial electrode to a cooling range within which the portion of the sacrificial electrode is actively cooled, where the entry point at a side opposite to the discharge area of ​​the sacrificial electrode side of the cooling range, and the cooling means is adapted that during operation of the device, in particular during stationary operation of the device, the average temperature of the sacrificial electrode at the entry point 393 K, preferably 373 K, preferably 323 K and, most preferably does not exceed 293 K. For these average temperatures of the sacrificial electrode in the entry region in particular, the difference between the average temperature of the sacrificial electrode within the discharge region of the sacrificial electrode and the average temperature of the can

Sacrificial electrode at the entry point in the range of T s - 393 K to Ts - 77 K, preferably T s - 373 K to T s - 77 K, more preferably from T s - 323 K to T s - 77 K, and most preferably from Ts - 293 K to T s - 77 K, are. The cooling means may be so arranged that the during operation of the device, in particular during stationary operation of the device, the average temperature of the sacrificial electrode within the discharge region

Sacrificial electrode does not exceed the melting temperature of the material of the sacrificial electrode.

The sacrificial electrode may have an elongated shape and in particular be designed as a wire, rod or hollow profile.

The apparatus may further comprise a detection device, in particular an optical and / or electronic detection device, such as an endoscope include, that is adapted to detect the position of the discharge region of the sacrificial electrode, especially optically and / or electronically.

The device may furthermore control means comprise adapted to the sacrificial electrode, in particular based on the detected by the detector position of the Enttadungsbereichs the sacrificial electrode to lead either to move to the position of the discharge region of the sacrificial electrode during operation of the device, in particular during stationary operation of the device, in spite of the process-related material removal, it remains substantially the same.

The voltage source may be so arranged that the discharge is a pulsed discharge. The

Spannungsquelie may be a DC voltage source or an AC power source. The voltage source may be a high voltage source,

The particles may μιτι a particle size in the range of 2 nm to 20, preferably μπη of 5 nm to 10, more preferably μιη from 10 nm to 5, more preferably μιτι from 10 nm to 1, and most preferably from 10 nm to 200 nm. The particle size of the particles can μηι also in a range of 2 nm to 10 2 nm μιη to 5, 5 nm to 5 mm, 2 nm to 1 mm, 5 nm to 1 pm, 2 nm to 200 nm, 5 nm to 200 nm, 20 nm to 200 nm or 50 nm to 200 nm.

The device of the invention is an apparatus for performing the method according to the invention. Therefore, the other features that have been set out in connection with the above description of the inventive method can also be applied to the inventive device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example with reference to the accompanying drawings, wherein

Figure 1 is a schematic cross-sectional view of a device according to a first

is embodiment of the present invention; Figure 2 is a schematic cross-sectional view of a portion of an apparatus according to a

second Ausführungsbeispie! of the present invention;

Figure 3 is a schematic cross-sectional view of a portion of an apparatus according to a third

is embodiment of the present invention; and

Figures 4 (a) and (b) are scanning electron micrographs of substrate surfaces, wherein Figure 4 (a) shows one without cooling of the sacrificial electrode coated with particles surface and Figure 4 (b) shows a surface coated with the inventive method with particles surface.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

1 shows a schematic cross-sectional representation of an apparatus for producing particles in an atmospheric pressure plasma according to a first embodiment of the present invention.

The apparatus shown in Figure 1 comprises a Piasmadüse 10, a gas supply means 20, a generator 22 as a power source, a cooling device 2, a detector 4 and a controller 6. The plasma nozzle 10 has an electrically conductive housing 5, which is preferably elongated, in particular tubular, is formed, and an electrically conductive nozzle head 32. The housing 5 and the nozzle head 32 form a through which a process gas 18 nozzle channel. 7

A sacrificial electrode 16 is provided so that it is partially disposed in the nozzle channel 7, through a wall of the nozzle channel 7, so the housing 5 passes, is guided through the cooling device 2 and is connected to the controller. 6 In the example shown in Figure 1, the sacrificial electrode 16 is formed as a wire electrode. In the nozzle channel 7, a tube 14 is of an insulator material such as a ceramic, is used.

The cooling device 2 can also be provided at a different location on or in the plasma 10th

In particular, the cooling device 2 can be located closer to the discharge region 17, for example within the schematically shown in Figure 1, an upper part of the sacrificial electrode 16 surrounding the cone-shaped casing.

By means of the generator 22, which is designed as a pulse generator, a voltage is applied between the sacrificial electrode 16 and the housing 5 / nozzle head 32nd The pulse frequency of the generator 22 are not particularly limited, and are preferably in the above in the general part of the description fields. Between the generator 22 and the sacrificial electrode 16 is advantageously a rectifier (not shown) are switched. The housing 5 and the nozzle head 32 are in the example shown in Figure 1 Ausführungsbeispie! grounded.

The process gas 18 is the Gaszufiihreinrichtung 20 in the Düsenkana! 7 and introduced so that it swirl shape passes though in the example shown in Figure 1 embodiment through the nozzle channel. 7 The drailförmige or wirbeiförmige flow of the process gas 18 is illustrated in Figure 1 by the spiral line 26th Such a flow of the process gas 18 may be achieved by a Dralieinrichtung 12th It may be a plate with holes or L manuals.

By a voltage applied from the generator 22 between the sacrificial electrode 16 and the housing 5 / nozzle head 32 high voltage is a discharge, particularly an arc discharge, ignited by the sacrificial electrode 16 to the not covered with the insulating tube 14 of the housing, here the nozzle head 32, , The discharge region 17 of the sacrificial electrode 16, ie the region of the sacrificial electrode 16, in which the discharge takes place predominantly is the tip, as illustrated schematically in Figure 1,

By the discharge is from the top of sacrificial electrode 16, that is removed from the discharge area 17, material. arising from the eroded particles of material 30, preferably micro- and nanoparticles, which are transported with the gas flow wirbeiförmigen 28th

The detection device 4 is provided as the optical detecting means, for example as endoscopic camera, and formed at an inner side of the tube fourteenth The detection means 4 is adapted to detect the position of the discharge region 17 of the sacrificial electrode 16 optically.

The control device 6 comprises, for example a stepping motor or a piezo element for guiding or moving the sacrificial electrode 16 and a control circuit, including a processor, and is adapted to move the sacrificial electrode 16 along the longitudinal direction of the sacrificial electrode 16 forward or backward.

The control device 6 is connected via a feedback circuit 8 to the detection device. 4 On

Erfassungssignat, indicating the position of the discharge region 17 of the sacrificial electrode 16 is supplied from the detection means 4 via the feedback circuit 8 of the control circuit of the controller. 6 Based on this Erfassungssignats the control circuit controls the stepping motor or the piezoelectric element 16 to move the sacrificial electrode so that the position of the discharge region 17 remains relative to the housing 5 during operation of the device, in particular during stationary operation of the device is substantially equal to therefore, does not deviate from a predetermined position.

A portion of the sacrificial electrode 16 which is arranged outside the housing 5 is, in the cooling device 2 is brought into direct contact with a cooling medium 11, such as water or liquid nitrogen, and thus cooled. The cooling medium 11 is supplied through lines 13 of the cooler 2 and discharged therefrom. For example, 2 to a cooling water circuit via the lines 13 (not shown), the cooling device can be connected.

Various types of cooling mögtiche the sacrificial electrode by means of a cooling device will be explained in detail below with reference to Figures 2 and 3. FIG.

By actively cooling the arranged outside the housing 5 portion of the sacrificial electrode 16 in the cooling device 2, a high temperature difference between this portion and the discharge portion 17, so that an efficient and rapid heat removal from the discharge region 17 is created.

In particular, the cooling device 2 is arranged so that in operation of the apparatus, the difference between the average temperature of the Opfereiektrode 16 within the Entiadungsbereichs 17 of the sacrificial electrode 16 and the average temperature of the sacrificial electrode 16 at an entry point 21 at which the sacrificial electrode 16 in a cooling region, namely, the cooling device 2, enters, in the range of Ts - 373 K to Ts - 77 K, where T is the melting temperature of the material of the sacrificial electrode 16 in K. In this way, a particularly fast and efficient heat dissipation from the discharge area 17 can be achieved.

Thus, the apparatus 30 may be operated according to the first embodiment of the present invention with high power inputs to the sacrificial electrode 16, and thus a high production rate of the particles, the particles 30 have a low Partikelgröfie and a controlled and defined particle size distribution.

As follows from the above, generated during operation of the apparatus shown in Figure 1, a plasma in the process gas 18 through a discharge between the sacrificial electrode 16 and the housing 5 / nozzle head 32nd By this discharge 16 material is removed from the sacrificial electrode, resulting from the prior to the deposition on the substrate surface particles 30th

A portion of the sacrificial electrode 16 is cooled by the cooling means 2 is active so that the average temperature of the sacrificial electrode 16 in a region of the sacrificial electrode 16 outside of the discharge region 17 of the

Opfereiektrode 16 is lower than within the discharge region 17 of the sacrificial electrode 16. Consequently, the method according to the invention with the device according to the first embodiment in a particularly efficient and simple manner can be performed.

The particles 30 are transported from the wirbeiförmigen gas flow 28 and exit through an outlet 36 of the nozzle head 32 from the plasma nozzle 10 out. Thus, the particles may be applied hergesteilten 30 via the outlet 36 selectively to the surface of a substrate 50, as shown schematically in FIG. 1 As indicated by the arrow 52 in Figure 1, in this case, the substrate 50 may be moved relative to the plasma nozzle 10, whereby a controlled local application of the particles 30 is enabled on the surface of the substrate 50,

The substrate 50 may, for example, from plastic, such as a polymer, or of wood, glass or ceramic.

Figure 2 shows a schematic cross-sectional view of a portion of an apparatus for producing particles in an atmospheric pressure plasma according to a second embodiment of the present invention.

The construction of the device according to the second embodiment differs from that of the apparatus according to the first embodiment substantially in that the sacrificial electrode 16 'is inserted through a side wall 9 of a housing of a plasma nozzle in a formed in the housing nozzle channel T.

15 by a discharge between the sacrificial electrode 16 'and a counter electrode (not shown) such as a conductive portion of a housing of the apparatus, for. B. a conductive nozzle head (z. B. as the nozzle head 32 in Figure 1), in a process gas in the nozzle channel 7 'is material (not shown) from the discharge region 17', so the top of the sacrificial electrode 16 formed as a wire electrode ' removed and transported further through the process gas along the nozzle channel 7 '. The material can be in particulate form or formed during the transportation, that is prior to the deposition on the substrate surface, particles 30 therefrom.

As indicated by the arrow A in Figure 2, the sacrificial electrode 16 'may by a control device to be moved such as the control device 6 of the device according to the first embodiment, in the direction perpendicular to the wall 9 of the nozzle channel 7 1 back and forth. Consequently, the sacrificial electrode 'may be performed so that the position of the discharge region 17' 16 during operation of the device, in spite of the process-related material removal, remains substantially the same.

The apparatus according to the second embodiment of the present invention comprises a cooling device 2 '. The cooling device 2 'is set up so that in operation of the apparatus, the difference between the average temperature of the sacrificial electrode 16' within the discharge region 17 'of the sacrificial electrode 16' and the average temperature of the sacrificial electrode 16 'at an entry point 21' at which the sacrificial electrode 'occurs in the range of T s - 373K to Ts - 77 K, where T s is the melting temperature of the material of the sacrificial electrode 16' 16 'in the' cooling means 2 is in K. In this way, a particularly fast and efficient heat dissipation from the discharge area can be achieved 17 '. The cooling device 2 comprises a housing 23 inside which a chamber 24 is formed, and two lines 13 ', which communicate with the chamber 24 in fluid communication. The sacrificial electrode 16 'is guided via two seals 19 through the chamber 24 and is held as movable by the seals 19 in that it in the direction perpendicular to the wall 9 of the channel 7' can be moved.

Via the lines 13 ', a gaseous or liquid cooling medium 1V, such as water or liquid nitrogen, the chamber 24 is supplied to and discharged from the chamber 24th For example, the lines may be 13 'connected to a cooling water circuit.

In the chamber 24, the cooling medium 11 comes' with a portion of the sacrificial electrode 16 ', which is arranged outside the housing of the device in direct contact and thereby cools the sacrificial electrode 16'. The resulting high temperature difference between the portion of the sacrificial electrode 16 'outside the housing and the discharge region 17' ensures quick and efficient removal of heat from the discharge region 17 '.

The portion of the sacrificial electrode 16 'can within the cooling device 2' may be taken from a thermally conductive material in a tube or the like. In this case, the cooling of the portion of the sacrificial electrode 16 'occurs via a thermal contact of the section with the cooling medium 11' on the tube.

Figure 3 shows a schematic cross-sectional view of a portion of an apparatus for producing particles in an atmospheric pressure plasma according to a third embodiment of the present invention.

The construction of the device according to the third embodiment differs from that of the apparatus according to the second embodiment mainly by the structure of the cooling device used, as explained in detail below.

The sacrificial electrode 16 "is by a side wall 9 'of a housing of a plasma nozzle in a nozzle channel formed in the housing 7" introduced. By a discharge 15 'between the sacrificial electrode 16 "and the housing in a process gas in the nozzle channel 7" material (not shown) from the discharge region 17 ", so the head of the constructed as a wire electrode sacrificial electrode 16", removed and along with the process gas of the nozzle channel 7 transported further. "the material may be present in particulate form öderes arise during transport, so prior to the deposition on the substrate surface, particles 30 therefrom.

As indicated by the arrow A 'is indicated in Figure 3, the sacrificial electrode 16 may "by a controller such as the controller 6 of the apparatus according to the first embodiment, in the direction perpendicular to the wall 9' of the channel 7" moves back and forth become. Consequently, the sacrificial electrode may "be performed so that the position of the discharge region 17" 16 during the operation of the apparatus, despite the prozessdingten Materiaiabtrages, remains substantially the same.

The apparatus according to the third embodiment of the present invention comprises a Kühieinrichtung 2 ". The Kühieinrichtung 2" is set up so that in operation of the apparatus, the difference between the average temperature of the sacrificial electrode 16 "within the discharge region 17" of the sacrificial electrode 16 "and the mean temperature of the sacrificial electrode 16 "at an entry point 21" on which the sacrificial electrode enters 16 "in the Kühieinrichtung 2", in the range of Ts - 77 K, wherein Ts is the melting temperature of the material of the sacrificial electrode 16 "in K - 373 K to Ts is. In this way, a particularly fast and efficient heat dissipation from the discharge area 1 "can be achieved.

is shown schematically in Figure 3, the wall 9 'of the housing of the device, which can for example have a cylindrical shape, a cavity or chamber 25, which run along a portion of the circumference of the housing or along the entire circumference of the housing can. The Kühieinrichtung 2 "two lines comprises 13" through which a gaseous or liquid cooling medium 11 'may be supplied, such as water or liquid nitrogen, the chamber 25 and discharged from the chamber the 25th example, the leads 13' connected to a cooling water circuit become.

The sacrificial electrode 16 " 'is passed through the chamber 25 and through the seals 19' via two seals 19 held so movable that it is movable along the direction perpendicular to the wall 9 'of the housing. In the chamber 25 of the section is the sacrificial electrode 16, "the outside of the channel 7" is arranged, cooled with the cooling medium 11 'in direct contact and thereby. By so resulting high

Temperature difference between the portion of the sacrificial electrode 16 "outside the duct 7" and the

Discharge area 17 "is a quick and efficient removal of heat from the discharge area 17 '

guaranteed.

The portion of the sacrificial electrode 16 "may be within the Kühieinrichtung 2" in a tube or the like from a thermally conductive materia! be added. In this Fal! The cooling of the portion of the sacrificial electrode 16 "via a thermal contact of the section with the cooling medium 11" via the tube.

Figure 4 shows scanning electron micrographs of glass slides as the substrate surfaces, were deposited on the silver particles. The deposition of the particles was carried out by means of an embodiment shown in Figure 2 apparatus having a sacrificial electrode 16 'made of silver, wherein the in Figure 4 the silver particles (a), without cooling the sacrificial electrode 16 and in Figure 4 {b) silver particles shown with active cooling of the sacrificial electrode 16 were separated 'by the Kühieinrichtung 2'. The scanning electron micrographs shown in Figure 4 were each at a

Electrons high voltage (EHT; "Electron High Tension"). Was added 5.00 kV, the distance between the substrate and scanning electron microscope was 2.6 mm in the in Figure 4 (a), measurement and in which, in Figure 4 (b), measuring 4 , 0 mm.

As the figure 4 it can be seen, allows the active cooling of the sacrificial electrode 16 'the production of significantly smaller or finer particles. Moreover, could the deposition rate, ie the rate at which a predetermined amount is deposited on material on a unit area, in which in Figure 4 (b), the substrate compared with that in Figure 4 (a), the substrate increased by a factor of approximately 12 become. This substantial increase in the rate of deposition is enabled by the 'achieved by cooling the sacrificial electrode 16 increase the production rate of the particles.

The process of the invention by the device of the invention and the achievable high

Partikelherstellraten, small particle size, and homogeneous particle size distributions enable the use of the particles produced in a variety of applications, such as in the medical sector, for household appliances, for hygiene articles and electronic elements, for example in battery technology.

The method and apparatus according to the invention may be used on substrate surfaces for depositing layers, in particular dense nanoparticle films. Moreover, particles can be incorporated into layers such as plasma polymer layers. As another possibility, the particles produced can be collected, for example by a powder separator, and then further uses are supplied,

For example, a non-cytotoxic and antimicrobial coating may be incorporated by the apparatus and method according to the invention, silver nanoparticles in plasma polymer layers to produce. Similarly, the zinc particles can be incorporated into plasma polymer layers to form an active corrosion protection for metals that are above the voltage range, that is more noble than zinc. A similar use is also possible with magnesium particles.

UV-absorbing particles such as ZnO particles, can be incorporated as UV-absorbing scratch protection in plasma polymer layers.

The significant aspects of the present invention will be summarized again:

(1) Process for the preparation of particles using an atmospheric pressure plasma, particularly in an atmospheric-pressure plasma, wherein the plasma is generated by a discharge between electrodes in a process gas, at least one of the electrodes is a sacrificial electrode is removed from the through the discharge material, it is at the ablated material to particles and / or arising from the eroded material particles, and a portion of the sacrificial electrode is actively cooled so that the average temperature of the sacrificial electrode in an area of ​​the sacrificial electrode outside the discharge area of ​​the sacrificial electrode is lower than within the discharge area of ​​the sacrificial electrode.

(2) The method of item (1), in which occurs the cooling of the portion of the sacrificial electrode via thermal conduction.

(3) The method of item (1) or (2), wherein the cooling of the portion of the sacrificial electrode is made by a cooling medium.

(4) The method of item (3), wherein the cooling medium contacts only the portion of sacrificial electrode outside the discharge region of the sacrificial electrode into contact.

(5) The method according to any of the preceding points, wherein the sacrificial electrode entering at an entry point of the sacrificial electrode to a cooling region in which the portion of the sacrificial electrode is actively cooled, where the entry point at a side opposite to the discharge area of ​​the sacrificial electrode side of the cooling range, and the difference between the mean temperature of the sacrificial electrode within the discharge region of the sacrificial electrode and the average temperature of the sacrificial electrode at the entry point in the range of Ts -393 K to Ts - 77 K, preferably from Ts - 373 K to Ts - 77 K, preferably from Ts - 323 K to Ts - 77 K, and most preferably from Ts - 293 K to Ts - 77 K, lies, wherein Ts is the melting temperature of the material of

Victims electrode in K.

(6) A method according to any of the preceding points, wherein the Opfereiektrode enters at an inlet Steep the sacrificial electrode to a cooling region in which the portion of the sacrificial electrode is actively cooled, where the entry point on an opposing the Entladungsbereäch the sacrificial electrode side of the cooling range, and the mean temperature of the sacrificial electrode to the admission Steep 393 K, preferably 373 K, preferably 323 K 293 K, and most preferably does not exceed.

(7) A method according to any one of the preceding items, wherein the mean temperature of the sacrificial electrode does not exceed the melting temperature of the material of the sacrificial electrode within the Entiadungsbereichs the Opfereiektrode.

(8) The method according to any one of the preceding items, wherein the Opfereiektrode has an elongated shape.

(9) A method according to any one of the preceding points, wherein the position of the UNLOAD is detected ungsbereichs the sacrificial electrode.

(10) The method of item (9), in which the position of the discharge region of the sacrificial electrode is detected optically and / or electronically.

(11) A method according to any of the preceding points, wherein the Opfereiektrode is performed so that the position of the Entiadungsbereichs the sacrificial electrode during the process remains essentially the same.

(12) The method of item (11) as a function of item (9) or (10) wherein said sacrificial electrode is performed based on the detected position of the discharge region of the sacrificial electrode so that the position of the

Entiadungsbereichs the sacrificial electrode during the process remains essentially the same.

(13) A method according to any of the preceding points, wherein the discharge is a pulsed discharge.

(14) A process in which μΐη the particles have a particle size in the range of 2 nm to 20 of the preceding points.

(5) The method according to any of the preceding points, wherein done generating the atmospheric pressure plasma, the removal of the material and the formation of particles using a plasma nozzle.

(16) The method according to any one of the preceding items, in particular according to item (15), arise in the particles in a relaxation region of atmospheric pressure plasma from the removed material. (17) The method according to any one of the preceding items, in particular according to item (15) or (16), wherein the residence time of the material is controlled in a relaxation region of the atmospheric pressure plasma.

(18) An apparatus for Hersteilung of particles using an atmospheric pressure plasma, particularly in an atmospheric-pressure plasma, comprising: a housing having a channel, at least two electrodes which are at least partially disposed in the channel, a voltage source which is adapted to a voltage to be applied between the at least two electrodes, wherein the at least two electrodes are adapted to generate the plasma by a discharge between the electrodes in a process gas in the duct, at least one of the electrodes, a sacrificial electrode, is removed from the through the discharge material, and it concerns with the ablated material to particles and / or arising from the eroded material particles, and a cooling device which is configured to actively cool a portion of the Opfereiektrode so that the average temperature of the sacrificial electrode in an area of ​​the sacrificial electrode outside of the discharge is sbereichs the sacrificial electrode is lower than within the discharge region of the Opfereiektrode.

(19) The apparatus of item (18), wherein the cooling means is adapted to cool the portion of the sacrificial electrode via thermal conduction.

(20) The apparatus of item (18) or (19), wherein the cooling means is adapted to cool the portion of the sacrificial electrode by a cooling medium.

(21) The apparatus of item (20), wherein the cooling means is arranged so that the cooling medium contacts only the portion of sacrificial electrode outside the discharge region of the sacrificial electrode into contact, in particular directly or via a wall in thermal contact. (22) A device according to any one of (18) to (21) wherein said sacrificial electrode entering at an entry point of the Opfereiektrode in a cooling region in which the portion of the sacrificial electrode is actively cooled, where the entry point at one of the Entiadungsbereich the sacrificial electrode opposite side of the cooling range, and the cooling device is set up so that in operation of the apparatus, the difference between the average temperature of the Opfereiektrode within the discharge region of the sacrificial electrode and the average temperature of the Opfereiektrode at the entry point in the range of Ts - 393 K to Ts - 77 K, preferably from Ts - 373 K to Ts - 77 K, more preferably from Ts - 323 K to Ts - 77 K, and most preferably from Ts - 293 K to Ts - 77 K, lies, wherein Ts is the melting temperature of the material of the sacrificial electrode is in K.

(23) A device according to any one of (18) to (22) wherein said sacrificial electrode entering at an entry point of the sacrificial electrode to a cooling region in which the portion of the sacrificial electrode is actively cooled, where the entry point at one of the Entiadungsbereich the Opfereiektrode opposite side of the cooling range, and the cooling device is set up so that in operation of the device, the average temperature of the sacrificial electrode at the entry point 393 K, preferably 373 K, preferably 323 K and, most preferably does not exceed 293 K.

(24) A device according to any one of (18) to (23), wherein the cooling means is arranged so that in operation of the device, the average temperature of the sacrificial electrode within the discharge region of the

Sacrificial electrode does not exceed the melting temperature of the material of the sacrificial electrode.

(25) A device according to any one of (8) to (24) wherein said sacrificial electrode has an elongate shape.

(26) A device according to any one of (18) to (25), further comprising a detecting means which is adapted to detect the position of the discharge region of the O ferelektrode.

(27) The apparatus of item (26), wherein the detection means is adapted to detect the position of the discharge region of the sacrificial electrode optically and / or electronically.

(28) A device according to any one of (18) to (27), further comprising a control means which is adapted to guide the sacrificial electrode so that the position of the UNLOAD ungsbereichs the sacrificial electrode during operation of the device remains substantially the same , (29) The apparatus of item (28) as a function of item (26) or (27), wherein the control means is adapted to perform the sacrificial electrode based on the detected by the detector position of the discharge region of the sacrificial electrode so that the position of the discharge region of the Opfereiektrode remains the same during operation of the device substantially.

(30) A device according to any one of (18) to (29), wherein the Spannungsqueile is so arranged that the discharge is a pulsed discharge.

in μηι exhibit (31) A device according to any one of (18) to (30), the particles have a particle size in the range of 2 nm to 20th

Claims

generates '(5, 32, 16 "in a process gas (18) 1. A method for producing particles (30) using an atmospheric-pressure plasma, wherein the plasma by a discharge (15, 15) 16, 16) between electrodes' is at least one of the electrodes, a sacrificial electrode (16, 16 ', 16 "), it is removed from the discharge through the material, it is in the ablated material! consists of particles and / or arising from the eroded material particles, and a portion of the sacrificial electrode is actively cooled so that the average temperature of the sacrificial electrode in a region of the sacrificial electrode outside the Entladungsberetchs (17, 17 ', 17 ") of the sacrificial electrode is lower as within the discharge region of the sacrificial electrode.
2. The method of claim 1, wherein the cooling of the portion of the sacrificial electrode made via heat conduction.
3. The method of claim 1 or 2, wherein the cooling of the portion of the sacrificial electrode by a cooling medium (11, 11 ', 11 ") is carried.
4. The method of claim 3, wherein the cooling medium comes into contact only with the region of the sacrificial electrode outside the discharge region of the sacrificial electrode.
5. The method according to any one of the preceding claims, wherein
the sacrificial electrode to an entry point (21, 2Γ, 21 ") of the sacrificial electrode enters a cooling region in which the portion of the sacrificial electrode is actively cooled, where the entry point is located on a side opposite to the discharge area of ​​the sacrificial electrode side of the cooling region, and the difference between the average temperature of the sacrificial electrode within the discharge region of the sacrificial electrode and the average temperature of the sacrificial electrode at the entry point in the range of Ts - 393 K to Ts - 77 K, where T is the melting temperature of the material of the sacrificial electrode in K.
6. The method according to any one of the preceding claims, wherein the Opfereiektrode entering at an entry point of the sacrificial electrode to a cooling region in which the portion of the sacrificial electrode is actively cooled, where the entry point at a side opposite to the discharge area of ​​the sacrificial electrode side of the cooling range, and does not exceed average temperature of the sacrificial electrode at the entry point 393 K.
7. The method according to any one of the preceding claims, wherein the mean temperature of the sacrificial electrode does not exceed the melting temperature of the material of the sacrificial electrode within the Entiadungsbereichs the Opfereiektrode.
8. The method according to any one of the preceding claims, wherein the sacrificial electrode has an elongated shape.
9. Method according to one in which the position of the discharge region of the sacrificial electrode is detected of the preceding claims.
10. The method of claim 9, wherein the position of the discharge region of the sacrificial electrode is detected optically and / or electronically.
11. The method according to one in which the sacrificial electrode is guided so that the position of the discharge region of the sacrificial electrode remains the same during the process substantially of the preceding claims.
12. The method according to claim 11 as dependent on claim 9 or 10, wherein the Opfereiektrode is performed based on the detected position of the discharge region of the sacrificial electrode so that the position of the discharge region of the sacrificial electrode remains the same during the process substantially.
13. The method according to any one of the preceding claims, wherein the discharge is a pulsed discharge.
14. A method according to any one of the preceding claims, wherein the particles have a Partike grofie μητι comprise up to 20! In the range of 2 nm.
15. The method according to any one of the preceding claims, arising from the particles in a relaxation region of atmospheric pressure plasma from the removed material.
16. The method according to one in which the residence time of the material is controlled in a relaxation region of the atmospheric pressure plasma of the preceding claims.
17. An apparatus for Hersteilung of particles (30) using an atmospheric-pressure plasma, comprising: a housing (5) having a channel (7, 7 ', 7 "), at least two electrodes (16, 16', 16"; 5, 32) which are at least partially disposed in the channel, a voltage source (22) which is adapted to apply a voltage between the at least two electrodes, wherein the at least two electrodes are adapted to the plasma by a discharge (15, 15 'to produce) between the electrodes (in a process gas 18) in the channel, at least one of the electrodes, a sacrificial electrode (16, 16', 16 "), it is removed from the through the discharge material, and at the removed material consists of particles and / or arising from the eroded material particles, and a Kühlei nrichtung (2) which is configured to actively cool a portion of the sacrificial electrode so that the average temperature of the sacrificial electrode in a region of the heads relektrode outside the
Discharge area (17, 17 ', 17 ") of the sacrificial electrode is lower than within the discharge region of the sacrificial electrode.
PCT/EP2014/072106 2013-10-15 2014-10-15 Method and device for producing particles in an atmospheric pressure plasma WO2015055711A1 (en)

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